Cyanine dyestuff



Patented Jan. 11, 1944 UNITED STATES PATENT OFFICE CYANINE DYESTUFF Oskar Riester, Dessau, Germany; vested in the Alien Property Custodian 6 Claims.

My present invention relates to new cyanine dyestuffs.

It is known that cyanine dyestuff ar produced by condensing a nitrogenous heterocyclic base having a reactive methyl or methylene group with a dimethylaminobenzaldehyde. These dyestuifs which are different from most of the other dyestuffs owing to the specially intensive tint of their colorings can, however, sufficiently dye merely wool, silk, and cotton treated with a mordant whereas the coloring of other fabrics as, for instance, acetate silk yields pale tints only.

The present invention is based on the observation that extremely intensive colorings can also be obtained with acetate silk by means of dyestuffs prepared by condensing nitrogenous heterocyclic bases having a reactive methyl or methylene group With halogen-hydroxybenzaldehydes containing in the hydroxy groups in the 2- and/ or 4-positions and the halogen atoms in the 3- and/or (a-positions. Moreover, the halogen-hydroxy-benzaldehydes may carry further substituents as, for instance, alkyl, alkoxy, thioalkyl or carboxyl groups. The dyestuffs thus prepared have the following general formula:

wherein A is a grouping of molecules necessary to complete a or 6-membered ring usual in cyanine dye art, such as indoline, thiazole, oxazole, quinoline, lepidine, benzimidazole, thiodiazole, isofurodiazole, selenazole and the like; these rings may be substituted by 'alkyl, aryl, benzyl, phenylene, naphthalene, substituted phenyls or heterocyclic nuclei or condensed with aromatic or heterocyclic rings; R is alkyl, aryl, aralkyl, alkylene, alkylenecarboxylic acid; R1 and R2 are hydroxyl groups or one of R1 and R2 is hydroxyl whereas the other substituent is hydrogen, alkyl, alkoxy, thioalkyl, carboxyl or another radicle; R3 and R4 are halogen groups or one of R3 and R4 is halogenand the other substituent-is hydrogen, alkyl, alkoxy, thioalkyl, carboxyl or another radicle; R5 is hydrogen, alkyl, alkoxy, thioalkyl, carboxyl or another substituent; X is an acid radicle as, for instance, Cl, Br, I, S04, C104, SOsCHx, SOsCzI-Is, SOsCeI-IaCHa.

The preparation of the dyestuffs is conveniently carried out by melting together the reactants in molecular proportions at an elevated temperature for about minutes to 2 hours with or without the employment of a solvent. It is advantageous to dissolve the fused mass in methanol, acetone or a similar solvent and split off 1 mol of acid from the dyestufi molecule by adding thereto basic agents, such as sodium-acetate, ammonia, so-

diumbicarbonate, piperidine or the li e so as to produce dyestufis forming especially purecrystals. The structure of these dyestuffs may be represented by the following formula of the quinoid It is, however, more accurate to give the dyestuffs a betaine-like structure of the intramolecular 'ionoid type:

The following example are illustrative of my invention but they are not intended to be limiting.

Example 1 A mixture of 3 g. of Z-methylbenzoxazole ethyliodide, 3 g. of 3.5-dibromo-4-hydroxy-benzalde- 40 hyde and 1 cc. of isoqui-noline is melted at 110 N Br Color of the methanolic solution: orange-yellow. Coloring of the acetate silk: orange-red.

Example 2 4 g. of 2-methyl-4.5-diphenylthiazole ethyliodide and 3 g. of 3.5-dibromo-4-hydroxybenzaldehyde are dissolved While boiling in a mixture of ,0 cc. pyridine .and20 cc.of alcohol. The-mass is then mixed with 2 cc. of piperidine and heated to 90 C. for 1 hour. On cooling the following dyestuff crystallizes out:

Color of the methanolic solution: red-violet. Col- Olll'lg of the acetate silk: red.

Example 3 A mixture of 4.5 g. of Z-methyI-B-naphthothiazole ethyl-iodide, 3 g. of 3.5-dibromo-4- hydroxybenzaldehyde, 20 cc. pyridine, 20 cc. of propanol, and 2 cc. of piperidine is boiled for half an hour. A dyestuff of the following formula crystallizes out:

Color of the methanolic solution: red-violet.

Absorption maximum: 550 m Color of the piperidine solution: blue-violet. Ab-

sorption maximum: 590 m Coloring of acetate silk: intensive red-violet.

Example 4 Absorption maximum: about 500 ma. Coloring of the acetate silk: yellow-orange.

Example 5 An orange-red dyestufi of the following constitution is obtained by means of 2.5-dimethylthiazole in an analogous manner to that as described in Example 4:

/S 1131' H3CC IHI C+-CH=CH OH OHaSOr- I? Br CH3 Coloring: orange-red.

Example 6' A mixture of s g. of quinoldine ethliodide, 3 g. of dibromohydroxybenzaldehyde, and 10 cc. of

pyridine is boiled for half an hour. A violet-red dyestuff of the following constitution crystallizes out:

Color of the solution: red-violet. Absorption maximum: about 550 nm.

Example 7 A mixture of equiinolecular amounts of 2-methylthiazoline methyliodide and 3.5-diiodol-hydroxybenzaldehyde and some drops of pyridine are melted together at 120 C. for 1 hour. The masss thus prepared is then dissolved in methanol. 0n addition of an ammonia solution of 1% strength a dyestuii of the following formula isv obtained.

l H2O H (I: C -CH=CH O- 4 BIT L CH3 Color of the methanolic solution and coloring:

pure-yellow.

Example 8 5 g. of 2.5.6-trimethylbenzselenazole ethyliodideare condensed with 5 g. of 3-bromo-4- hydroxybenzaldehyde in the presence of 10 cc. of pyridine. One obtains a red dyestuff of the following constitution:

Se moc+--o11=o11-Qo- HaC- .wl Br C2115 Example 9 5 g. of 12.3.3-tetramethylindoliniumperchlorate and 6 g. of 3.5-dichloro--hydroxybenzaldehyde are condensed by heating at C. for half an hour to form a violet-red dyestuff of the following constitution:

Al CL CHa A Coloring of acetate silk: intensive red.

. Example 10 A mixture of l g. of Z-methyl-G-phenylbenzoxazole and 5,2 g. diethylsulfate is heated at C. in an oil bath for one hour. 9 g. of 3.5-dibromol-hydroxybenzaldehyde and3 cc. of pyridine are then added to the mass and the whole is heated at 120 C. fora further hour. Finally the melt is dissolved in 280 cc. of a methanolic solution of sodium acetate of ,12,5%. On, standing an orange-red dyestufi of the following formula crystallizes out:

On replacing Z-methyl-B-phenylbenzoxazole in Example by 2-methyl-G-chlorobenzoxazole an analogous dyestufl likewise yielding an orangered solution and coloring and having the following formula is obtained:

5 g. of 2-methyl-1-phenyl-benzimidazole and 5 cc. of dimethylsulfate are heated at 140 C. in an oil bath for one hour. 8 g. of the sodium salt of 3.5-dibromo-4-hydroxybenzaldehyde (obtained by precipitating an aqueous alkaline solution of the dibromohydroxybenzaldehyde with a concentrated solution of sodium hydroxide in excess), cc. of pyridine and 5 cc. of piperidine are then added thereto and the whole is subsequently heated at 110 C. for 6 hours. After acidifying the mass with diluted acetic acid; the precipitated dyestuif is sucked off, dissolved in methanol and slowly mixed with ether. Orange-red crystals dissolving in pyridine with an orange-red color are obtained. The dyestuff has the following Absorption maximum in pyridine: 525 mg. Color of the methanolic solution: yellow.

Absorption maximum: 460 m Coloring: pureyellow.

Example 13 A mixture of 5 g. of 2-methylbenzthiazole-B- propionyl bromide, 4 g. of 2-methyl-3.5-dibromo- 4-hydroxybenzaldehyde and 2 cc. of pyridine is heated at 105 C. for half an hour. The melt is then rubbed together with propanol and the resulting dyestufi sucked off. It is of the follow ing formula:

Color of the solution and coloring: carmine red.

Example 14 5 g. of 2-methylbenzthiazole-p-propeionylbromide and 5 g. of 3-bromo-4-hydroxy-5-ethoxybenzaldehyde are condensed in the manner as described in Example 13 to form a dyestuff of the following constitution:

S Br I 10 g. of 3.5-dibromosalioylaldehyde are condensed with 20 g. of pyridine by heating for half an hour. The solution is then mixed with 5-times its weight of propanol and caused to crystallize out. The dyestufi thus obtained has the following formula:

S I c+on=cn 11- Coloring of wool and acetate silk: blue-violet.

Example 16 When in Example 15 3.5-dibromoresorcylaldehyde is used instead of 3.5-dibromosalicylaldehyde, a dyestuff yielding violet colorings and having the following constitution is produced:

s OH Br l HO Br III Br C2H5 I claim: 1. A dyestuff of the following general formula:

I R5 R4 wherein A means a grouping of molecules necessary to complete a ring selected from the class consisting of a 5-membered and a 6-membered ring usual in cyanine dye art; R means a radicle selected from the class consisting of alkyl, aryl, alkylenecarboxylic acid; R1 and R2 mean radicles selected from the class consisting of hydrogen and hydroxyl, at least one of said radicles always being hydroxyl; R3 and R4 mean radicles selected from the class consisting of hydrogen, halogen, and alkyl, oxyalkyl at least one of the said radicl es always being halogen; R5 means a radicle selected from the class consisting of hydrogen and alkyl; X means an anionic acid radicle.

2. Compounds of the following formula:

wherein A represents the atoms necessary to complete a nitrogenous heterocyclic nucleus of the type usual in cyanine dyes, hal is halogen, and X is an anion.

3. Compounds of the following formula:

5. The compounds defined in claim 3 wherein A represents the atoms necessary to complete a thiazole nucleus.

6. Compounds of the following formula:

l 01 alkyl wherein A represents the atoms necessary to complete a nitrogenous heterocyclic nucleus of the type usual in cyanine dyes, and X is an anion.

OSKAR RIESTER. 

